This invention relates generally to valves for use in connection with respirators or like apparatus suitable for use in resuscitation and, more particularly, to a valve apparatus for use in connection with such apparatus for providing a stepless or continuous adjustment of the counter-pressure presented to expiration by the patient.
It is often advisable or necessary in connection with providing respiration by means of a respirator or like apparatus to be able to adjust the counter-pressure which is presented to the expiration of exhalation of the patient. In this connection, it is highly desirable to be able to adjust the extent of the counter-pressure presented during respiration in a stepless or continuous manner so that the most advantageous counter-pressure may be utilized under the particular circumstances.
In the present applicant's Finnish patent application No. 753,748, a respirator apparatus is disclosed which is provided with an expiration valve and wherein the counter-pressure to expiration by the patient is adjustable in a stepless or continuous manner. In this design, the expiration valve is located directly over the drug atomizer. The expiration valve includes a sleeve which is located between the mouthpiece of the respirator and the drug atomizer in which a flap, located at the end of the sleeve distal from the mouthpiece, is adapted to open on inspiration and close on expiration.
An aperture is formed in the sleeve which leads to the expiration valve. The sleeve is adapted to be rotated to achieve a stepless adjustment of the counter-pressure presented during expiration.
The expiration valve disclosed in the above-identified patent application further includes a diaphragm which functions to inhibit the outward flow through the exit aperture of the expiration valve during inspiration but which allows the inhalant, such as air or oxygen and atomized drugs, to pass from the exit ports or apertures at exhalation.
The design of the expiration valve described above is, however, not entirely satisfactory. More particularly, the expiration valve described above has a relatively complex construction which is necessarily costly in manufacture. Moreover, the location of the expiration valve directly over the drug atomizer seriously restricts the use thereof in connection with certain respirators. Thus, where respirators are assembled of standard components constituting a type of modular system, it is not always possible to utilize the expiration valve described above in association therewith. Still further, the placement of the expiration valve over or on top of the drug atomizer also restricts the various options normally available in connection with the assembly and modification of the respirator.